Means for elimination of end play in a sewing machine

ABSTRACT

A construction and arrangement for operably combining in a unique manner a thrust bearing and a spring washer to substantially eliminate undesirable end play in the arm shaft of a sewing machine during its operation.

J Umted States Patent 1 13,552,338

[721 lnventor Thomas G. Graham [56] References cued Jersey UNITED STATES PATENTS [21] Appl. No. 831,023 J 6 Larsh [45] Patented Jan. 5,1971 2,703,737 3/1955 Turner 308/163 [73] Assignee The Singer Company 3,058,436 10/1962 Goosman 1 12/158 New York: NY Primary Examiner-H. Hampton Hunter corpora"!!! Of New J y Attorneys-Marshall .l. Breen, Chester A. Williams, Jr. and F I Donald Paris [54] MEANS FOR ELIMINATION OF END PLAY IN A SEWING MACHINE 4 Claims, 6 Drawing Figs.

52 us. Cl. 112/218,

308/163 ABSTRACT: A construction and arrangement for operably [51] Int. Cl D05b 69/32 combining in a unique manner a thrust bearing and a spring [50] Field of Search 112/218, washer to substantially eliminate undesirable end play in the 220, 158; 308/163, 164; 74/(lnquired) arm shaft of a sewing machine during its operation.

PATENTEU MN 5 I SHEET 1 UF 2 INVENTOR. Thomas G. Graham BY I ATTORNEY PATENTED JAN 519m I 3552,3138

- saw 2 UF 2 INVENTOR. Thomas 6. Graham MEANS FOR ELIMINATION OF END PLAY IN A SEWING MACHINE SUMMARY The present invention relates to sewing machines and more particularly to a novel and improved construction for eliminating shaft end play in a sewing machine.

Incident to the operation of any sewing machine there is a certain amount of end play or in other words, a back-and-forth endwise movement, of its arm shaft. The arm shaft extends through the horizontal portion of the arm terminating in the balance or hand wheel at one end, and in the needle bar crank at the other end. It is the main drive shaft being drivingly secured directly to the source of power and all moving parts of the machine are actuated from this shaft by means of connecting rods, gears, or belts. The shaft normally is supported at two or more points, preferably proximate each extremity, by sleeve or ball bearings located in the arm castings. Numerous sewing machine models carry the eccentrics for driving the feed motion, through forked or closed end connecting rods, and the gears or cranks or sprockets for conveying power to the mechanisms located in the bed of the machine. Thus, as the driven arm shaft operably drives the various parts of the sewing machine, the movement of these parts is such as to create a certain amount of endwise movement in the arm shaft. Because such endwise movement of the arm shaft adversely may affect the operation of the sewing machine and in particular may generate excessive noise due to the intermittent loads applied to the shaft, it is essential to substantially eliminate such undesirable arm shaft movement.

Thus, it is a primary object of the present invention to provide novel and improved means. for substantially eliminating end play in a shaft of a sewing machine during its operation.

Another object of the present invention is to provide means for eliminating end play in the arm shaft of a sewing machine during its operation, which means is relatively easy to assemtale and adjust, and is efficient, dependable and durable.

Having in mind the above andother objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the functions, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a vertical sectional view longitudinally of a sewing machine embodying the present invention;

FIG. 2 is a view partly in section illustrating an enlargement of the portion of the arm shaft of FIG. lat the hand wheel end; FIG. 3 illustrates an exploded perspective view of the present invention;

FIGS. 4 and 4A illustrate side and end elevational views, respectively, of a spring washer forming a part of the present invention; and

- FIG. 5 illustrates in section another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more specifically to the drawings, wherein like reference numerals designate similar parts throughout the various views, the preferred embodiment of this invention is incorporated in a zigzag or ornamental stitch sewing machine forming the subject matter of the US. Pat. No. 3,05 l ,107, assigned to the assignee of the present invention, wherein the machine is fully disclosed and to which reference may be had for a more complete understanding thereof. In FIG. I there is illustrated a sewing machine having a frame comprising a bed 10, a standard I] rising from one end of the bed and carrying a bracket arm 12 that tenninates in a head 13 overhanging the bed 10.

Arranged longitudinally of the bracket arm 12 is a main shaft 14 which at the head end is journaled in and radially supported by a bearing bushing 15 mounted in a transverse wall 16 between the bracket arm 12 and the head I3, and at the standard or hand wheel end is journaled in and radially supported by a bearing bushing 17 mounted in a transverse wall 18 in the top of the standard 11. On the standard end of the main shaft 14 outwardly of the bushing 17 there is mounted in conventional fashion a combined hand wheel and belt pulley 19 that releasably is clamped to the shaft by the usual clamp stop motion screw and washer generally designated 20. The

combined hand wheel and pulley is mounted on a flanged bushing 21 secured by means of a screw 22 to the main shaft 14. A driving belt 23 operably connects the belt pulley 19 with a standard sewing machine motor 24 mounted in conventional fashion in the standard 11.

In the head 13 there is mounted, in a conventional manner, for endwise reciprocation and lateral vibration a needle bar 25 carrying at its lower end a needle 26. The needle bar 25 is supported in a conventional manner in a swinging needle bar gate (not fully shown) having a pair of vertically spaced lugs (not shown) pivotally mounted on a vertical axis pivot rod (not shown) carried by bosses (not shown). The needle bar gate has a pair of vertically spaced lugs 27 and 28 in which the needle bar 25 is mounted for endwise movement and such movement is imparted thereto through a crank 29 connected by a link 30 to a collar 31 secured on the needle bar.

In the usual manner upon endwise reciprocation of the needle bar 25, the needle 26 penetrates work disposed on the throat plate 32 and cooperates with a standard stitch forming mechanism generally designated 33 including a loop taker 34 of the vertical axis oscillating hook type. Oscillation is imparted to the loop taker 34 by a vertical axis shaft 35 journaled in the standard 11 and gear connected at its upper end to the main shaft 14. At its lower end, the, shaft 35 carries a crank 36 connected to one end of a pitman 37 having its other end connected to one arm (not shown) of a bellcrank lever pivotally mounted by a pivot screw 38 on a bracket 39 in which is journaled the hook shaft 40. The bellcrank lever has a second arm 41 connected by a link 42 to a crank 43 secured on the lower end of the hook shaft 40.

A conventional four motion feeding mechanism generally designated 44 is provided for advancing the work across the work supporting surface of the machine past the point of stitch formation. Basically, the mechanism 44 includes a feed bar 45 pivotally connected at one end to a rocker (not shown) on a feed advance rock shaft (not shown) that is oscillated in the usual manner by a pitman 46 actuated by an eccentric 47 on the main shaft 14.Feed lift motions are imparted to the feed bar 45 in a conventional manner by a feed lift shaft 48 having at one end an arm 49 connected by a link 50 to the feed bar and having at the other end an arm 51 carrying a cam follower 52 that tracks an axial displacement cam surface 53 on top of the crank 36.

To accomplish the desired ornamental stitching the needle bar mounted in the swinging gate is designed to be vibrated laterally of the line of feed and toward this end a pitman 54 is connected conventionally in pivotal fashion at one end to the needle bar gate. Thus, endwise movement of the pitman imparts oscillation to the needle bar gate, thereby imparting lateral vibration to the needle bar. The other end of the pitman is connected conventionally to a cam follower 55 that tracks the cam surface of a driven ornamental stitch pattern cam 56. The cam 56 is mounted on' a rotatable cam shaft 57 drivingly connected to the main shaft 14 through a worm wheel 58 which meshes with a worm 59 on the main shaft.

From the above description it is apparent that the main shaft 14 drives a variety of movable parts, each of which has a predetermined type of movement. Thus, certain of the moving parts, such as the cam 56, contribute a'component of movement in the axial direction of the main shaft, while other moving parts, such as the feedeccentric 47, contribute a component of movement radially of the main shaft. Also, it is recognized because of the irregular movement of the various parts that these driven parts do not provide a constant load for the main shaft, but on the contrary define an intermittent or variable loading effect on the shaft dependent upon the particular operation being performed by the sewing machine. Thus, for example, the lateral vibration of the needle bar induced by the particular selected cam surface is a variable loading factor, as is the eccentrically driven feeding mechanism. The combined effect ofthese factors tends to cause a certain amount of end play or undesirable axial movement of the main shaft. The collar 60 mounted on the main shaft inwardly of the bushing 15 together with the crank 29 do not adequately serve to limit the end play within a certain permissible amount since the vibration of the main shaft caused by the variable loading thereon will cause the collar to loosen. Thus, as shown in FIG. 1, there is provided at the standard end of the main shaft means for substantially eliminating this undesired end play. Toward this end, as best illustrated in FIG. 2, there is provided on the main shaft between the bushing 17 and the flanged bushing 21 a thrust bearing, generally designated 61, including pair of disc-shaped washers 62 functioning as races located on either side of the bearing 63 and a spring washer 64 having a wavelike configuration located between one of the washers 62 andthe flanged bushing 21. In a first embodiment at the head end of the main shaft there is provided between the crank 29 and the bushing 15 a recess 65 formed in the crank 29 for receiving a second thrust bearing 66 similar in construction to the thrust bearing 61. The thrust bearing 61 initially is preloaded by compressing the spring washer 64 a predetermined amount. In the embodiment of FIGS. 1 and 2 the amount of compression is determined by the axial space provided between the bushing 17 and the flanged bushing 21, which in turn depends on the length of each of the aforementioned bushings. The second thrust bearing 66 simultaneously is preloaded by compression. of the washer due to the transfer of the compression force axially along the main shaft 14. The preloading force applied to the thrust bearings is made greater in value than that required during normal operation of the machine so that when the machine is operable the preoperative thrust force will decrease to a value that substantially will eliminate undesirable end play in the main shaft. Thus, the variable loading along the main shaft will be absorbed by the spring washer 64.

Another embodiment of this invention is illustrated in FIG. 5 and comprises locating the thntst bearing 61 and spring washer 64, which in the previous embodiment was located at the standard end of the main shaft, at the head end of the main shaft between the bushing and the collar 60 held in place by a set screw 67. By proper adjustment of the collar 60 from the dotted position (before compression) to its solid line position (after compression) the washer 64 is compressed as discussed before and the resultant-effect, that is, elimination of end play in the main shaft during operation of the sewing machine is obtained. A spacer member 68, if necessary, may be provided between the bushing 15 and the adjacent disc- Y shaped washer to provide the proper desired spacing between the former andthe collar 60.

Numerous alterations of the. structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of our invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

Iclaim;

1. In a sewing machine having a frame, a needle-carrying needle bar mounted in said frame for endwise reciprocation actuating means and said needle-carrying needlebar for transmrtting motion thereto, a first arm shaft bushing, 581d first bushing radially supporting said arm shaft, a second arm shaft bushing transversely spaced a predetermined distance from said first bushing, the space defined by said second bushing relative to said first bushing including a plurality of contiguously axially disposed components comprising a thrust bearing having a pair of races axially disposed on either side thereof, a spring washer located directlylbetween one of said races and one of said bushings, said thrust bearing being preloaded by locating said bushings relative to each other on said arm shaft so that said spring washer is compressed a predetermined amount whereby the force applied to said washer causing it to become compressed a predetermined amount is transferred to said thrust bearing and is greater in value prior to operation of the machine than the value of force required during normal operation of said machine so that the resultant thrust force is decreased during operation of the machine to a value desired for proper machine operation, whereby any end play in the arm shaft of said sewing machine is substantially eliminated.

2. In a sewing machine according to claim 1 wherein a second thrust bearing is located on said arm shaft at the end opposite from the first mentioned thrust bearing, whereby the compression force applied to said springwasher simultanecluding a main arm shaft operatively disposed between said actuating means and said needle-carrying needle bar for transmitting motion thereto, an arm shaft bushing, said bushing radially supporting said arm shaft, an axially adjustable arm shaft collar transversely spaced from said bushing, the space defined by said arm shaft collar relative to said arm shaft bushing including a plurality of contiguous axially disposed components comprising a thrust bearing having a pair of races axially disposed on either side thereof, a spring washer located directly between one of said races and said arm-shaft collar, said thrust bearing being preloaded by axially adjusting said arm shaft collar so that said spring washer is compressed a predetermined amount whereby the force applied to said washer causing it to become compressed a predetermined amount is transferred to said thrust bearing and is greater in value prior to operation of the machine than the value of force required during normal operation of said machine so that the resultant thrust force is decreased during operation to a value whereby the compression force applied to said spring washersimultaneously is transferred axially along said arm shaft to said second thrust bearing. 

1. In a sewing machine having a frame, a needle-carrying needle bar mounted in said frame for endwise reciprocation and lateral vibration, work feeding means carried on said frame, actuating means for operably driving said needle-carrying needle bar and said work feeding means, said frame including a main arm shaft operatively disposed between said actuating means and said needle-carrying needle bar for transmitting motion thereto, a first arm shaft bushing, said first bushing radially supporting said arm shaft, a second arm shaft bushing transversely spaced a predetermined distance from said first bushing, the space defined by said second bushing relative to said first bushing including a plurality of contiguously axially disposed components comprising a thrust bearing having a pair of races axially disposed on either side thereof, a spring washer located directly between one of said races and one of said bushings, said thrust bearing being preloaded by locating said bushings relative to each other on said arm shaft so that said spring washer is compressed a predetermined amount whereby the force applied to said washer causing it to become compressed a predetermined amount is transferred to said thrust bearing and is greater in value prior to operation of the machine than the value of force required during normal operation of said machine so that the resultant thrust force is decreased during operation of the machine to a value desired for proper machine operation, whereby any end play in the arm shaft of said sewing machine is substantially eliminated.
 2. In a sewing machine according to claim 1 wherein a second thrust bearing is located on said arm shaft at the end opposite from the first mentioned thrust bearing, whereby the compression force applied to said spring washer simultaneously is transferred axially along said arm shaft to said second thrust bearing.
 3. In a sewing machine having a frame, a needle-carrying needle bar mounted in said frame for endwise reciprocation and lateral vibration, work feeding means carried in said frame, actuating means for operably driving said needle-carrying needle bar and said work feeding means, said frame including a main arm shaft operatively disposed between said actuating means and said needle-carrying needle bar for transmitting motion thereto, an arm shaft bushing, said bushing radially supporting said arm shaft, an axially adjustable arm shaft collar transversely spaced from said bushing, the space defined by said arm shaft collar relative to said arm shaft bushing including a plurality of contiguous axially disposed components comprising a thrust bearing having a pair of races axially disposed on either side thereof, a spring washer located directly between one of said races and said arm shaft collar, said thrust bearing being preloaded by axially adjusting said arm shaft collar so that said spring washer is compressed a predetermined amount whereby the force applied to said washer causing it to become compressed a predetermined amount is transferred to said thrust bearing and is greater in value prior to operation of the machine than the value of force required during normal operation of said machine so that the resultant thrust force is decreased during operation to a value desired foR proper machine operation, whereby any end play in the arm shaft of said sewing machine is substantially eliminated.
 4. In a sewing machine according to claim 3 wherein a second thrust bearing is located on the side of said arm shaft bushing opposite from the first mentioned thrust bearing, whereby the compression force applied to said spring washer simultaneously is transferred axially along said arm shaft to said second thrust bearing. 